The pilot of a plane that crashed in Nigeria's largest city of Lagos, killing all 153 people on board, was an American and the co-pilot was Indian, Nigeria's civil aviation chief said on Monday. Asked to confirm whether the pilot was an American, Harold Demuren told AFP, "that's true." He said the co-pilot was Indian. Demuren said the cause of the crash remained unclear. He said the flight declared an emergency with the tower on approaching Lagos' airport, but he said he was not yet aware of the details of the emergency. The Dana Air MD83 crashed in a densely populated area of Lagos on Sunday afternoon. Besides the 153 people on board, others were believed killed on the ground, but figures were not yet available. Dana Air is a Nigerian domestic airline.